//邮件发送:

using (SmtpClient sc = new SmtpClient("smtp.163.com"))
            {
                //收件人  (可以多个)
                mm.To.Add("5***@qq.com");
                mm.To.Add("*****@qq.com");
                //邮件正文
                mm.Body = "大家好,我是XXX";
                //发件者邮箱
                mm.From = new MailAddress("88888@163.com");
                //邮件标题
                mm.Subject = "测试邮箱";
                //如果启用SSL
                //sc.EnableSsl = true;
                //如果启用了客户端授权码,要使用授权码代替密码(用户名和密码)(授权码:163COM)
                sc.Credentials = new System.Net.NetworkCredential("8888@163.com", "163COM");
                //发送
                sc.Send(mm);
            }